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ipv6: hook up exception table to store dst cache

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This commit makes use of the exception hash table implementation to
store dst caches created by pmtu discovery and ip redirect into the hash
table under the rt_info and no longer inserts these routes into fib6
tree.
This makes the fib6 tree only contain static configured routes and could
now be protected by rcu instead of a rw lock.
With this change, in the route lookup related functions, after finding
the rt6_info with the longest prefix, we also need to search for the
exception table before doing backtracking.
In the route delete function, if the route being deleted is not a dst
cache, deletion of this route also need to flush the whole hash table
under it. If it is a dst cache, then only delete the cached dst in the
hash table.

Note: for fib6_walk_continue() function, w->root now is always pointing
to a root node considering that fib6_prune_clones() is removed from the
code. So we add a WARN_ON() msg to make sure w->root always points to a
root node and also removed the update of w->root in fib6_repair_tree().
This is a prerequisite for later patch because we don't need to make
w->root as rcu protected when replacing rwlock with RCU.
Also, we remove all prune related variables as it is no longer used.

Signed-off-by: Wei Wang <weiwan@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wei Wang 2017-10-06 12:06:03 -07:00 committed by David S. Miller
parent 38fbeeeecc
commit 2b760fcf5c
4 changed files with 72 additions and 133 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/ip6_fib.h
View File

@ -280,7 +280,6 @@ struct fib6_walker {
struct fib6_node *root, *node;
struct rt6_info *leaf;
enum fib6_walk_state state;
bool prune;
unsigned int skip;
unsigned int count;
int (*func)(struct fib6_walker *);

1
net/ipv6/addrconf.c
View File

@ -2326,7 +2326,6 @@ static struct rt6_info *addrconf_get_prefix_route(const struct in6_addr *pfx,
if (!fn)
goto out;
noflags |= RTF_CACHE;
for (rt = fn->leaf; rt; rt = rt->dst.rt6_next) {
if (rt->dst.dev->ifindex != dev->ifindex)
continue;

95
net/ipv6/ip6_fib.c
View File

@ -54,7 +54,6 @@ struct fib6_cleaner {
#define FWS_INIT FWS_L
#endif
static void fib6_prune_clones(struct net *net, struct fib6_node *fn);
static struct rt6_info *fib6_find_prefix(struct net *net, struct fib6_node *fn);
static struct fib6_node *fib6_repair_tree(struct net *net, struct fib6_node *fn);
static int fib6_walk(struct net *net, struct fib6_walker *w);
@ -1101,6 +1100,8 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt,
if (WARN_ON_ONCE(!atomic_read(&rt->dst.__refcnt)))
return -EINVAL;
if (WARN_ON_ONCE(rt->rt6i_flags & RTF_CACHE))
return -EINVAL;
if (info->nlh) {
if (!(info->nlh->nlmsg_flags & NLM_F_CREATE))
@ -1192,11 +1193,8 @@ int fib6_add(struct fib6_node *root, struct rt6_info *rt,
#endif
err = fib6_add_rt2node(fn, rt, info, mxc);
if (!err) {
if (!err)
fib6_start_gc(info->nl_net, rt);
if (!(rt->rt6i_flags & RTF_CACHE))
fib6_prune_clones(info->nl_net, pn);
}
out:
if (err) {
@ -1511,19 +1509,12 @@ static struct fib6_node *fib6_repair_tree(struct net *net,
read_lock(&net->ipv6.fib6_walker_lock);
FOR_WALKERS(net, w) {
if (!child) {
if (w->root == fn) {
w->root = w->node = NULL;
RT6_TRACE("W %p adjusted by delroot 1\n", w);
} else if (w->node == fn) {
if (w->node == fn) {
RT6_TRACE("W %p adjusted by delnode 1, s=%d/%d\n", w, w->state, nstate);
w->node = pn;
w->state = nstate;
}
} else {
if (w->root == fn) {
w->root = child;
RT6_TRACE("W %p adjusted by delroot 2\n", w);
}
if (w->node == fn) {
w->node = child;
if (children&2) {
@ -1557,12 +1548,17 @@ static void fib6_del_route(struct fib6_node *fn, struct rt6_info **rtp,
RT6_TRACE("fib6_del_route\n");
WARN_ON_ONCE(rt->rt6i_flags & RTF_CACHE);
/* Unlink it */
*rtp = rt->dst.rt6_next;
rt->rt6i_node = NULL;
net->ipv6.rt6_stats->fib_rt_entries--;
net->ipv6.rt6_stats->fib_discarded_routes++;
/* Flush all cached dst in exception table */
rt6_flush_exceptions(rt);
/* Reset round-robin state, if necessary */
if (fn->rr_ptr == rt)
fn->rr_ptr = NULL;
@ -1625,18 +1621,9 @@ int fib6_del(struct rt6_info *rt, struct nl_info *info)
WARN_ON(!(fn->fn_flags & RTN_RTINFO));
if (!(rt->rt6i_flags & RTF_CACHE)) {
struct fib6_node *pn = fn;
#ifdef CONFIG_IPV6_SUBTREES
/* clones of this route might be in another subtree */
if (rt->rt6i_src.plen) {
while (!(pn->fn_flags & RTN_ROOT))
pn = pn->parent;
pn = pn->parent;
}
#endif
fib6_prune_clones(info->nl_net, pn);
}
/* remove cached dst from exception table */
if (rt->rt6i_flags & RTF_CACHE)
return rt6_remove_exception_rt(rt);
/*
* Walk the leaf entries looking for ourself
@ -1679,16 +1666,14 @@ static int fib6_walk_continue(struct fib6_walker *w)
{
struct fib6_node *fn, *pn;
/* w->root should always be table->tb6_root */
WARN_ON_ONCE(!(w->root->fn_flags & RTN_TL_ROOT));
for (;;) {
fn = w->node;
if (!fn)
return 0;
if (w->prune && fn != w->root &&
fn->fn_flags & RTN_RTINFO && w->state < FWS_C) {
w->state = FWS_C;
w->leaf = fn->leaf;
}
switch (w->state) {
#ifdef CONFIG_IPV6_SUBTREES
case FWS_S:
@ -1820,20 +1805,16 @@ static int fib6_clean_node(struct fib6_walker *w)
* func is called on each route.
* It may return -1 -> delete this route.
* 0 -> continue walking
*
* prune==1 -> only immediate children of node (certainly,
* ignoring pure split nodes) will be scanned.
*/
static void fib6_clean_tree(struct net *net, struct fib6_node *root,
int (*func)(struct rt6_info *, void *arg),
bool prune, int sernum, void *arg)
int sernum, void *arg)
{
struct fib6_cleaner c;
c.w.root = root;
c.w.func = fib6_clean_node;
c.w.prune = prune;
c.w.count = 0;
c.w.skip = 0;
c.func = func;
@ -1858,7 +1839,7 @@ static void __fib6_clean_all(struct net *net,
hlist_for_each_entry_rcu(table, head, tb6_hlist) {
write_lock_bh(&table->tb6_lock);
fib6_clean_tree(net, &table->tb6_root,
func, false, sernum, arg);
func, sernum, arg);
write_unlock_bh(&table->tb6_lock);
}
}
@ -1871,22 +1852,6 @@ void fib6_clean_all(struct net *net, int (*func)(struct rt6_info *, void *),
__fib6_clean_all(net, func, FIB6_NO_SERNUM_CHANGE, arg);
}
static int fib6_prune_clone(struct rt6_info *rt, void *arg)
{
if (rt->rt6i_flags & RTF_CACHE) {
RT6_TRACE("pruning clone %p\n", rt);
return -1;
}
return 0;
}
static void fib6_prune_clones(struct net *net, struct fib6_node *fn)
{
fib6_clean_tree(net, fn, fib6_prune_clone, true,
FIB6_NO_SERNUM_CHANGE, NULL);
}
static void fib6_flush_trees(struct net *net)
{
int new_sernum = fib6_new_sernum(net);
@ -1914,32 +1879,6 @@ static int fib6_age(struct rt6_info *rt, void *arg)
return -1;
}
gc_args->more++;
/* The following part will soon be removed when the exception
* table is hooked up to store all cached routes.
*/
} else if (rt->rt6i_flags & RTF_CACHE) {
if (time_after_eq(now, rt->dst.lastuse + gc_args->timeout))
rt->dst.obsolete = DST_OBSOLETE_KILL;
if (atomic_read(&rt->dst.__refcnt) == 1 &&
rt->dst.obsolete == DST_OBSOLETE_KILL) {
RT6_TRACE("aging clone %p\n", rt);
return -1;
} else if (rt->rt6i_flags & RTF_GATEWAY) {
struct neighbour *neigh;
__u8 neigh_flags = 0;
neigh = dst_neigh_lookup(&rt->dst, &rt->rt6i_gateway);
if (neigh) {
neigh_flags = neigh->flags;
neigh_release(neigh);
}
if (!(neigh_flags & NTF_ROUTER)) {
RT6_TRACE("purging route %p via non-router but gateway\n",
rt);
return -1;
}
}
gc_args->more++;
}
/* Also age clones in the exception table.

108
net/ipv6/route.c
View File

@ -878,8 +878,8 @@ static struct rt6_info *ip6_pol_route_lookup(struct net *net,
struct fib6_table *table,
struct flowi6 *fl6, int flags)
{
struct rt6_info *rt, *rt_cache;
struct fib6_node *fn;
struct rt6_info *rt;
read_lock_bh(&table->tb6_lock);
fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
@ -893,6 +893,11 @@ static struct rt6_info *ip6_pol_route_lookup(struct net *net,
if (fn)
goto restart;
}
/* Search through exception table */
rt_cache = rt6_find_cached_rt(rt, &fl6->daddr, &fl6->saddr);
if (rt_cache)
rt = rt_cache;
dst_use(&rt->dst, jiffies);
read_unlock_bh(&table->tb6_lock);
@ -1592,7 +1597,7 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
int oif, struct flowi6 *fl6, int flags)
{
struct fib6_node *fn, *saved_fn;
struct rt6_info *rt;
struct rt6_info *rt, *rt_cache;
int strict = 0;
strict |= flags & RT6_LOOKUP_F_IFACE;
@ -1624,6 +1629,10 @@ struct rt6_info *ip6_pol_route(struct net *net, struct fib6_table *table,
}
}
/*Search through exception table */
rt_cache = rt6_find_cached_rt(rt, &fl6->daddr, &fl6->saddr);
if (rt_cache)
rt = rt_cache;
if (rt == net->ipv6.ip6_null_entry || (rt->rt6i_flags & RTF_CACHE)) {
dst_use(&rt->dst, jiffies);
@ -1988,23 +1997,17 @@ static void __ip6_rt_update_pmtu(struct dst_entry *dst, const struct sock *sk,
if (!rt6_cache_allowed_for_pmtu(rt6)) {
rt6_do_update_pmtu(rt6, mtu);
/* update rt6_ex->stamp for cache */
if (rt6->rt6i_flags & RTF_CACHE)
rt6_update_exception_stamp_rt(rt6);
} else if (daddr) {
struct rt6_info *nrt6;
nrt6 = ip6_rt_cache_alloc(rt6, daddr, saddr);
if (nrt6) {
rt6_do_update_pmtu(nrt6, mtu);
/* ip6_ins_rt(nrt6) will bump the
* rt6->rt6i_node->fn_sernum
* which will fail the next rt6_check() and
* invalidate the sk->sk_dst_cache.
*/
ip6_ins_rt(nrt6);
/* Release the reference taken in
* ip6_rt_cache_alloc()
*/
dst_release(&nrt6->dst);
if (rt6_insert_exception(nrt6, rt6))
dst_release_immediate(&nrt6->dst);
}
}
}
@ -2068,7 +2071,7 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
int flags)
{
struct ip6rd_flowi *rdfl = (struct ip6rd_flowi *)fl6;
struct rt6_info *rt;
struct rt6_info *rt, *rt_cache;
struct fib6_node *fn;
/* Get the "current" route for this destination and
@ -2093,8 +2096,23 @@ static struct rt6_info *__ip6_route_redirect(struct net *net,
continue;
if (fl6->flowi6_oif != rt->dst.dev->ifindex)
continue;
if (!ipv6_addr_equal(&rdfl->gateway, &rt->rt6i_gateway))
/* rt_cache's gateway might be different from its 'parent'
* in the case of an ip redirect.
* So we keep searching in the exception table if the gateway
* is different.
*/
if (!ipv6_addr_equal(&rdfl->gateway, &rt->rt6i_gateway)) {
rt_cache = rt6_find_cached_rt(rt,
&fl6->daddr,
&fl6->saddr);
if (rt_cache &&
ipv6_addr_equal(&rdfl->gateway,
&rt_cache->rt6i_gateway)) {
rt = rt_cache;
break;
}
continue;
}
break;
}
@ -2785,9 +2803,9 @@ static int __ip6_del_rt_siblings(struct rt6_info *rt, struct fib6_config *cfg)
static int ip6_route_del(struct fib6_config *cfg,
struct netlink_ext_ack *extack)
{
struct rt6_info *rt, *rt_cache;
struct fib6_table *table;
struct fib6_node *fn;
struct rt6_info *rt;
int err = -ESRCH;
table = fib6_get_table(cfg->fc_nlinfo.nl_net, cfg->fc_table);
@ -2801,13 +2819,17 @@ static int ip6_route_del(struct fib6_config *cfg,
fn = fib6_locate(&table->tb6_root,
&cfg->fc_dst, cfg->fc_dst_len,
&cfg->fc_src, cfg->fc_src_len,
true);
!(cfg->fc_flags & RTF_CACHE));
if (fn) {
for (rt = fn->leaf; rt; rt = rt->dst.rt6_next) {
if ((rt->rt6i_flags & RTF_CACHE) &&
!(cfg->fc_flags & RTF_CACHE))
continue;
if (cfg->fc_flags & RTF_CACHE) {
rt_cache = rt6_find_cached_rt(rt, &cfg->fc_dst,
&cfg->fc_src);
if (!rt_cache)
continue;
rt = rt_cache;
}
if (cfg->fc_ifindex &&
(!rt->dst.dev ||
rt->dst.dev->ifindex != cfg->fc_ifindex))
@ -2933,8 +2955,14 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
nrt->rt6i_protocol = RTPROT_REDIRECT;
nrt->rt6i_gateway = *(struct in6_addr *)neigh->primary_key;
if (ip6_ins_rt(nrt))
goto out_release;
/* No need to remove rt from the exception table if rt is
* a cached route because rt6_insert_exception() will
* takes care of it
*/
if (rt6_insert_exception(nrt, rt)) {
dst_release_immediate(&nrt->dst);
goto out;
}
netevent.old = &rt->dst;
netevent.new = &nrt->dst;
@ -2942,17 +2970,6 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu
netevent.neigh = neigh;
call_netevent_notifiers(NETEVENT_REDIRECT, &netevent);
if (rt->rt6i_flags & RTF_CACHE) {
rt = (struct rt6_info *) dst_clone(&rt->dst);
ip6_del_rt(rt);
}
out_release:
/* Release the reference taken in
* ip6_rt_cache_alloc()
*/
dst_release(&nrt->dst);
out:
neigh_release(neigh);
}
@ -3344,12 +3361,8 @@ static int fib6_clean_tohost(struct rt6_info *rt, void *arg)
{
struct in6_addr *gateway = (struct in6_addr *)arg;
/* RTF_CACHE_GATEWAY case will be removed once the exception
* table is hooked up to store all cached routes.
*/
if ((((rt->rt6i_flags & RTF_RA_ROUTER) == RTF_RA_ROUTER) ||
((rt->rt6i_flags & RTF_CACHE_GATEWAY) == RTF_CACHE_GATEWAY)) &&
ipv6_addr_equal(gateway, &rt->rt6i_gateway)) {
if (((rt->rt6i_flags & RTF_RA_ROUTER) == RTF_RA_ROUTER) &&
ipv6_addr_equal(gateway, &rt->rt6i_gateway)) {
return -1;
}
@ -3438,20 +3451,9 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg)
dst_metric_raw(&rt->dst, RTAX_MTU) &&
!dst_metric_locked(&rt->dst, RTAX_MTU)) {
spin_lock_bh(&rt6_exception_lock);
/* This case will be removed once the exception table
* is hooked up.
*/
if (rt->rt6i_flags & RTF_CACHE) {
/* For RTF_CACHE with rt6i_pmtu == 0
* (i.e. a redirected route),
* the metrics of its rt->dst.from has already
* been updated.
*/
if (rt->rt6i_pmtu && rt->rt6i_pmtu > arg->mtu)
rt->rt6i_pmtu = arg->mtu;
} else if (dst_mtu(&rt->dst) >= arg->mtu ||
(dst_mtu(&rt->dst) < arg->mtu &&
dst_mtu(&rt->dst) == idev->cnf.mtu6)) {
if (dst_mtu(&rt->dst) >= arg->mtu ||
(dst_mtu(&rt->dst) < arg->mtu &&
dst_mtu(&rt->dst) == idev->cnf.mtu6)) {
dst_metric_set(&rt->dst, RTAX_MTU, arg->mtu);
}
rt6_exceptions_update_pmtu(rt, arg->mtu);